A section insulator of this general type is known from WO 99/03700. Two aligned rigid conductor rails are shown there, the facing ends of which have a first space between each other. An electroconductive runner each is connected to these ends, with the two runners projecting into the first space, substantially running antiparallel (i.e., parallel but pointing in opposite directions) to each other in a second space/distance, with said second space/distance being selected such that at operating voltage of the conductor rails a safe electrical isolation is guaranteed which also means that no spark discharges between the runners can occur. The electroconductive runners and the adjacent conductor rails at least with their lower side facing the travel plane are arranged in a plane called contact plane. In relation to the running direction, i.e. the conductor rail longitudinal axis, the two electroconductive runners intersect, so that the collector of a vehicle when passing the section insulator is always in electrical contact with at least one of the runners and contacts it.
The known runners run inclined relative to the conductor rail longitudinal axes and have a free unsecured end each facing the opposing conductor rail. Insofar it is an open system. Moreover, the free ends of the electroconductive runners are each bent towards the top and away from the travel plane in order to achieve a gentle entry of the collector of a vehicle and to avoid a “threading” of the collector or a shock when reaching the free end of the runner.
In the area of the two antiparallel runners, however, there is the problem that on the hand due to the bent up free ends of the runners and on the other hand by not exact assembly only one runner of the collector is contacted. In the only small air gap between the runner not contacted but under voltage, an electric field is formed which is the greater, the smaller the air gap is. As a result of the great field strength in this area, a spark discharge may occur. But any spark discharge is undesired, since it causes successive burn-up and wear on the contact wire and on the collector and produces inductive voltage peaks which might damage the electric motor of the vehicle. If both runners are contacted, this occurs due to the inexactness mentioned with contact forces of different amounts, whereby contact resistances of different amounts and highly fluctuating in practice occur on both contact points between contact wire and collector which is undesired. Moreover, the runners, due to their free ends, on contact with the collector can be induced to mechanical vibrations also perpendicular to the travel plane leading again to air gaps as well as different contact forces. Above all, the very elastically carried contact strips on the collector are induced to mechanical vibrations.
Moreover, it may also happen that the point of contact between the runner and the collector “jumps” several times between the runner and the collector, causing each time an impulse to occur on the collector. This impulse is the greater, the greater the travelling speed is. Due to the large second distance necessary for electrical isolation between the two runners, the impulses are applied on the contact strip of the collector relative eccentrically, whereby the impulses occurring cause undesired torque impulses on the collector which is correspondingly strongly deflected.
EP 0 052 176 B1 shows a section insulator for contact wires attached on chain supporting structures, the opposing ends of which are spaced apart from each other. Both ends of the contact wires are connected with each other via parallel insulating strips which are contacted by the collector of a vehicle passing by. On the ends of the two contact wires a spark conductor is attached. In the transition area between the two contact wires the contact strip of the vehicle contacts only the insulating strips so that the vehicle has no power supply. Due to the inductance of the electric motors of the vehicle, high voltage peaks can occur. This is why the spark conductors are provided. Nevertheless, spark formation is undesired for the reasons mentioned above.
EP 0 592 819 B1 shows a section insulator for contact wires attached to catenary structures, the opposing ends of which are connected with each other by electrically insulated runners. On both ends of the contact wires arcing horns with runner ramps are attached which protrude into a first space between the two contact wires and have a second space/distance between each other. To one of the two arcing horns, electroconductive runners are connected, running parallel to the insulating runners and extending so far in the direction of the opposing arcing horn that the sectioning point between the two conductive runners is sufficiently bridged. The lower sides of the runner leads, the insulating runners and the conductive runners facing the travel plane shall be arranged precisely in one plane there and preferably be formed flat themselves. In addition, the two insulating runners shall still have an arc preventing means so that in total seven elements, namely two conductive runners, two insulating runners, two arc preventing means and one runner lead shall be contacted by the collector. It is difficult, however, to align seven elements precisely in one plane. Also, by different wear, such as for example abrasion or burn-up, the individual elements can be worn out unequal so that again air gaps and thus spark formation occurs between the contact strip and the electroconductive runners.
JP 60234034 A shows a section insulator for contact wires attached to catenary supporting structures, the ends of which in the area of the section insulator are deflected laterally opposed and run antiparallel and spaced apart from each other. The free ends of the contact wires are connected to the other contact wire in each case via an insulator. Moreover, the contact wires in the area of the section insulator are bent off from the travel plane towards the top so that they cross in side view. The contact strip of a vehicle passing by must follow the change in height, if a constant contact with the contact wire is to be maintained which is impossible at higher speeds. Hence, the problems described in the beginning occur as well.